• Exploitation and Survival of River Shannon Reared Salmon

      O'Maoileidigh, N; Browne, J; McDermott, T; Cullen, A; Bond, N; McEvoy, B; O'Farrell, M; O'Connor, W (Department of the Marine, 1994)
      Following the construction of the River Shannon hydroelectric scheme the Electricity Supply Board (ESB) have maintained a juvenile salmon restocking programme. Tagging of smolts with coded wire tags (microtags) was initiated in 1980 to examine the migration and survival of these stocked fish. In 1991, an estimated 292,000 hatchery reared salmon smolts (micro tagged and adipose finclipped) migrated from the River Shannon, County Limerick. This allowed an assessment to be made of the contribution of these fish to the high seas fisheries at West Greenland and Faroes, and also to homewater net and rod fisheries. Over 12,000 grilse from this release programme were estimated to have been taken by commercial nets with 525 taken on rods and 3,147 surviving to spawn. The return rate of 2 sea winter fish was much lower with 150 taken by commercial nets, 93 taken by rods and 202 estimated to have spawned. The Greenland fishery took approximately 107 potential 2 sea winter fish which is a high proportion of the overall 2 sea winter stock. Tag returns from groups of smolts released by helicopter proved to be highest. Groups released above the dams and which had to navigate through these installations also showed comparatively good returns. Early presmolt and smolt releases (i.e. December and February) did not give as good return rate in comparison to the other release groups.
    • Export and Import of Shellfish 1961-1970

      Gibson, F A (Department of Agriculture and Fisheries (Fisheries Division), 1972)
      The greater part of all varieties of shellfish and shellfish preparations, produced from Irish fisheries are exported. Markets for this production are located chiefly in Britain and Europe. The home market has been taking a steady proportion of some varieties, notably, lobsters, Dublin Bay prawns (Nephrops), crabs, oysters and escallops. At the same time, considerable quantities of shellfish are imported.
    • The fat content of Irish herring

      Molloy, J; Cullen, A (Department of Fisheries and Forestry (Trade and Information Section), 1981)
      The fat content in herrings determines the way in which these fish are presented for human consumption. For example, a high fat content is good for kippering, whilst low fat is suitable for marinating. The Department of Fisheries & Forestry has for many years provided the trade with the fat content data they require. The information is based on routine analyses of herring samples which are now made regularly at the Fisheries Research Centre. Sufficient data have been collected over the past ten years to prepare graphs of the mean monthly fat contents in our four main herring fisheries. These graphs may be used to estimate when herring of a particular fat content will be available. This Leaflet presents the essential data and gives an explanation of the biological background of the changes in fat content.
    • The Fat Contents of Irish Mackerel During 1984/85 and 1985/86

      Barnwall, E (Department of Tourism, Fisheries and Forestry, 1986-06)
      The fat contents of Irish mackerel in recent years (1983-1984) have been published by McArdle, Barrtwall and Nolan (Fishery Leaflet 129). Since then, routine analyses of mackerel including fat content have been continued during the 1984/85 and 1985/86 seasons and the results have been circulated to the trade. Because processors now attach considerable importance to fat contents, and because there have been suggestions that the fat content during 1985/86 may have been abnormally high, it has been decided to publish the complete results of all samples analysed during the last two fishing seasons.
    • First results from a new method of tagging salmon - the coded wire tag

      Browne, J (Department of Fisheries and Forestry (Trade and Information Section), 1981)
      This leaflet describes the use of a new and highly sophisticated method of tagging salmon. The tag is a microscopic piece of steel carrying a binary-coded number. It is injected into the nose of the young fish and can be recovered at any time subsequently by passing the fish through a magnetic detector. More than 127,000 juvenile salmon were tagged in 1979 and the first of these were recaptured as grilse in the summer of 1981. Research work initiated by Eileen Twomey in 1975 at the Fisheries Research Centre showed that hatchery-reared smolts were making a significant contribution to the national salmon catch. Hatchery-reared fish are recognised by the absence of the adipose fin which is clipped off before the fish are released. The adipose fin is generally thought to be rudimentary and its removal does not seem to affect the fish in any way. The results obtained showed that the proportion of hatchery-reared fish in the commercial catch varied from 2% in the Northwest to 13% on the Clare and Galway coasts. This work gave information on the contribution of hatcheries to the national salmon harvest. The Electricity Supply Board (ESB) have proposals to increase significantly the production of reared smolts for release. It is clearly essential to have information on the survival of hatchery salmon, on the efficiency of various rearing stations and on aspects of husbandry such as the best time for releasing the young fish. This information cannot be obtained by the fin-clipping technique alone but the coded wire tag can provide the answers to many of the vital questions.
    • Fish Kills 1969-1987

      McCarthy, D T (Department of the Marine, 1988)
      A total of 66 fish kills were reported to the Regional Fisheries Boards in 1986 and 122 in 1987. Effluents from agriculture and agriculture-based industries accounted for 56 of the kills in 1986 and 95 in 1987. When the two periods, 1969-74 and 1980-87 are compared, it can be seen that the numbers caused by sewage and industrial wastes have not changed significantly, but the damage from agriculture has risen at an alarming rate. The fact that problems from sewage and industry remained at a low level in the period, in spite of increasing urbanisation, suggests that measures to combat these sources of pollution have had some effect. Analysis of the fish kills shows clearly that the most urgent problem is to discover how silage effluent can be controlled.
    • Fish Kills in Ireland 1991-1992

      Moriarty, C (Department of the Marine, 1993)
      The numbers of fish kills were below the average for the ten years since the systematic recording of incidents began in 1983. Totals were 60 and 51 for 1991 and 1992 respectively. Both years therefore represent a continuation of the downward trend which began after the peak of 122 incidents in 1987. An important factor in the improved situation was the reduction in the number of silage discharges which had been the most serious problem for a number of years. Untreated sewage and industrial effluents in general have also shown downward trends. . Two serious problems remaining are 'enrichment' and run-off from farmyards, which includes spillage of slurry. Slurry and farm effluents in fact showed an increase in 1992 over 1991. Enrichment by excessive phosphorous, derived both from partially treated domestic sewage and from fertiliser, causes algal blooms leading to deoxygenation of the water and the death sometimes of very large numbers of fish - to say nothing of environmental conditions which are unacceptable to everybody who uses rivers or lakes. The effect of a discharge of effluent depends on many factors. In wet weather with high stream flows the damage will be minimised because the effluent is diluted quickly. A spillage beside a small river will led to a much more extensive fish kill than the same quantity of effluent will cause in a large one. These and other factors probably explain why, in spite of the small number of fish kills in 1992, nearly twice as much river was affected as in 1991.
    • Fish Kills in Ireland in 1985

      Fahy, E (Department of Tourism, Fisheries and Forestry, 1986-06)
      Fish kills reported by the water pollution officers of the Regional Fisheries Boards in 1985 are evaluated as were similar incidents in 1983 and 1984. Trout, Salmo trutta, was the species most widely implicated and the suspected cause of death was oxygen depletion resulting from agricultural activities. The small number of kills (37), compared with other years, was attributed to weather conditions and particularly to high rainfall in 1985. Contrary to expectation, the average numbers of fish killed in an incident were higher and the channel lengths affected were twice as long as in 1983 and 1984. Whether these findings represent a new pattern of water pollution is not known.
    • Fish Kills in Ireland in 1988

      McCarthy, D; Moriarty, C (Department of the Marine, 1989)
      The number of fish kills reported in 1988 showed a very welcome reduction to 50 incidents after the 1987 record of 122. The principal source of trouble has continued to be inadequately planned agricultural practices. Run-off from silage was once more the most serious problem, accounting for 13 kills. Slurry or manure accounted for seven more. While weather conditions may have alleviated the problem, due credit for the improvement must be given to the farmers who responded to the campaign organised by the Government in conjunction with the farming organisations. Industrial sources were responsible for 11 incidents. They have been increasing since 1985 but still remain below the maximum recorded in 1984. Sewage, for the first time since 1980, was not implicated. The most serious events in 1988 were on the Inny caused by an industrial effluent and on the Dodder following a discharge of silt from a water treatment plant.
    • Fish Kills in Ireland in 1989

      Moriarty, C (Department of the Marine, 1990)
      The final estimate for the number of fish kills in 1989 was 111. The increase in 1989 is largely accounted for by the exceptional warm weather conditions which prevailed. Details of all the incidents are given in the following pages. When these are analysed some very significant facts emerge. The number of fish kills while higher than in 1988 (50 kills) was about nine percent lower than in 1987 (122 kills). Low water due to dry weather conditions was the most important factor in 1989 raising the number of kills by 50%. Despite weather conditions, fish kills due to agricultural causes showed little change on the 1988 level - thus maintaining the substantial reduction in kills due to these causes achieved in 1988. As many as 50 of the incidents resulted from pollution which in a normal wet summer would not have caused such serious damage. These problems give a useful, if painful, reminder that water pollution can have devastating results. They also serve to highlight high risk situations. Many of the 1989 fish kills resulted from a shortage of oxygen from untraceable causes, for example from excessive plant growth due to fertiliser run-off or domestic sewage - or both. Others came from identifiable sources. In about half these cases the authorities felt that genuine accidents had happened and a warning to the guilty party was all that was needed. In others, twenty-seven in all, legal proceedings were set in motion.
    • Fish Kills in Ireland in 1990

      Moriarty, C (Department of the Marine, 1991-07)
      The total of 52 fish kills in 1990 was a marked improvement over the previous year when 111 were reported. Although this result was no better than that for 1988, it represented a considerable achievement because 1988 experienced a wet summer with high water flows while 1990 was exceptionally dry. Because of the poor dilution of pollutants, low river flows are usually associated with an increase in the number of fish kills. All three traditional causes of fish kills, agriculture, industry and sewage showed a downward trend. These have all been subjected to a campaign of information and enforcement of the regulations. This has brought about an increased awareness of the hazards and major improvements have been made in reducing the risks of accidental spillages. In spite of these efforts, the problem remains very serious. Although so much better than the peak figures of more than 100 fish kills in a single year, the level of 50 is unacceptably high. The analysis of the year's results shows that agricultural sources continue to cause extremely serious damage. The problem lies partly in the fact that a single accidental discharge into a salmonid nursery river can kill many thousands of fish for as much as 20 kilometres downstream. If the downward trend of problems from agriculture and industry can be maintained, the greatest threat in water pollution is likely to be that of enrichment, above all the release of excessive phosphate into the environment. Two sources, fertilizer and domestic sewage, are implicated. The sewage element can be controlled by upgrading treatment plants wherever necessary. The reduction of phosphate runoff requires continued attention to the information campaign for farmers to explain the: need for extreme care in fertilizer application. Remedial action in this case increases farm profits since all the fertilizer which pollutes the rivers is lost to the land.
    • Fish Kills in Ireland in 1993

      Moriarty, C (Department of the Marine, 1994)
      The pattern of fish kills in 1993 showed a dramatic change from that of the previous ten years. The number of incidents showed a very welcome reduction to a total of 33, the lowest since systematic records began to be kept in 1982. Only one case of damage caused by silage effluent was reported and two from farm effluents - in the recent past these were the most frequent and serious sources. However, fish kills provisionally attributed to 'enrichment' attained a record total of 16, most of them in the lakes in Co. Cavan in the Erne catchment. Sewage and runoff from agricultural land are the main sources of the phosphorous which brings about excessive blooms of microscopic algae. Enrichment has caused extremely serious problems in the past, in particular in Loughs Ennel and Sheelin. In both cases, remedial measures were successful, although problems have arisen again in the case of Lough Sheelin. The more widespread problem in the Erne catchment may be more difficult to contain and there are also signs of trouble in the Rivers Shannon and Lee. The trend of increasing numbers of enrichment-based fish kills does not necessarily mean that even more such incidents will take place in 1994 - but it is virtually certain that similar problems to those of 1993 will arise sooner or later unless action is taken.
    • Fish Kills in Ireland in 1994 and 1995

      Moriarty, C (Marine Institute, 1996-05)
      In 1994, the downward trend in numbers of fish kills continued, the total for the year being 32. However, in 1995 a long spell of dry weather greatly reduced the flow in rivers in all parts of Ireland and the number of fish kills rose to 84, the highest since 1989. In 1994, farmyard effluents, silage and slurry together accounted for one third of the fish kills. Industrial effluents and enrichment both caused 19% of the total. Storm water runoff and cement spillage in building operations were the other identified causes. In 1995, enrichment was the most frequent problem, followed by agriculture. Inadequately treated sewage was implicated in five cases and waterworks effluent in two. In 17 cases the mortalities were associated with reduced water flows or high temperatures or a combination of the two. The dry summer in a number of cases revealed unsatisfactory levels of pollution which are usually masked by higher water flows such as occurred in 1994. The increase in farm-based problems suggested that some of the improved facilities for storage and treatment of farm waste which were made in the late 1980s may now be due for maintenance. Enrichment of lake systems, particularly those of the Erne and Shannon, has now established itself as the most serious threat to the condition of natural waters. Fish kills are an early warning of a situation which may develop and have far-reaching effects on economic interests far removed from the fishery itself.
    • Fish Kills in Ireland: An Analysis of Incidents in 1983 and 1984

      Fahy, E (Department of Fisheries and Forestry, 1985-08)
      An analysis is presented of 200 fish kills recorded in 1983 and 1984. The reports which originated from various sources were corroborated by the water pollution officers of the Regional Fishery Boards. The incidents are evaluated by reference to similar information gathered by the Environmental Protection Agency of the United States of America. Shortcomings in the reporting of incidents include the lapse of time between the onset of a kill and its appraisal and the difficulties of establishing the facts retrospectively. The preponderance of trout among the mortalities might indicate a bias towards reporting incidents which involved this game species. The vast majority of kills occurred in rivers and about 65% took place in June and July, a pattern resembling that in the United States. Where the size of kill was recorded it averaged 269 fish, very small by U.S. standards. The average channel length affected by a fish kill was approximately 2.8 km (1.7 miles) (ranging between 0.01 and 25 km; 0.06 and 16 miles) and there was no relationship between the channel lengths and the numbers of mortalities.
    • Fisheries Research Centre: Report for 1992

      Department of the Marine (Department of the Marine, 1993)
      This report of the Fishery Research Centre's 1992 programme reflects not only the wide range of the work carried out, but also the extensive multidisciplinary expertise available at the FRC which we deploy in support of resource-based industries and other marine-oriented commercial enterprises. The report also provides information on the important scientific activities which the FRC has been able to initiate or expand by means of the valuable funding received under the EC STRIDE initiative. The £2.02 m allocated to the FRC over the period 1991-1993 (75% funded by the EC) is being used to carry out applied research in the three main areas of our responsibility - fish stocks, aquaculture and marine environment - in support of lreland’s marine based industries. Under STRIDE we have augmented the FRC staff by 23 people (a 50% increase) in order to implement this extended research programme. This intake of contract staff comprises 2 post-doctorates, 10 post-graduates, 8 laboratory technicians and 3 technical (clerical) assistants.
    • Fisheries Research Centre: Report for 1993

      Department of the Marine (Department of the Marine, 1994-11)
      Work carried out at the Fisheries Research Centre in 1993 reflects the impact of the first full year of support funding from the EC STRIDE initiative. As highlighted in the 1992 Report, the extra £2.02 million allocated to FRC (75% provided by the EC) enabled us to initiate or expand, in support of Irish marine-based industries, a broad range of scientific activities in the fields of marine fish stocks, aquaculture and the environment. The 1993 programme enabled by this extra research funding, as described in the following pages, is already yielding benefits on a national scale. More working contact with industry, increased data acquisition and big improvements in our analytical and reporting capabilities have enabled the FRC to provide a better service to management which has greatly strengthened Ireland's hand in negotiating for quotas and other benefits. The improved facilities have also led to an increase in our success rate in applying for European research funds. The success of STRIDE has demonstrated the value of a realistic scale of financial investment in a national programme of scientific R&D (research and development). Financial commitment must be maintained at the same level, or increased, if the benefits – already emerging –for our marine-based industries are to achieve their full impact in the years ahead.
    • Fisheries Research Centre: Report for 1994-1995

      Fisheries Research Centre (Marine Institute, 1997-03)
      This combined annual Report for the years 1994 and 1995 span a critical period in the history of the Fisheries Research Centre. During 1994 the funding support from the EC STRIDE Initiative came to an end, having achieved a notable and wholly innovative impact on marine R&D activities in Ireland. The scientific undertakings at the core of the STRIDE Programme have been maintained through a number of contract research positions at the FRC, where they continue to make a critical contribution to Irish marine science. The year 1995 marked the culmination of almost a century of fisheries related research carried out under the direct control of the Government Service, having been initiated in 1900 by the Department of Agriculture and Technical Instruction for Ireland. On 1 January 1996 the Fisheries Research Centre transferred to the Marine Institute, and thus this FRC Report is the first to be published under the new masthead. The future of Irish marine research, and in particular that part of it carried out at the Fisheries Research Centre, thus looks set to enjoy another boost to its continuing development, similar in impact to that created at the beginning of this century.
    • Freshwater Crayfish 1968

      Moriarty, C (Department of Agriculture and Fisheries (Fisheries Division), 1969)
      The freshwater crayfish inhabits some rivers and lakes in Ireland. The only species known to inhabit Ireland is Astacus palipes. It looks like a lobster but is very much smaller, seldom more than 10 cm (4 ins.) in length. As a rule it hides by day and comes out to hunt at dusk. Apart from the fact that it feeds on various kinds of dead animal matter nothing is known about its feeding habits in Ireland. In other parts of Europe it eats water weed and many kinds of small creatures. The crayfish can be caught easily in special traps which resemble small lobster pots and are baited with raw meat. Boiled crayfish are excellent food but are rarely eaten in Ireland. In other countries, especially Sweden, they are regarded as luxury items and are sold at high prices. Crayfish caught in Ireland for export to Sweden should be worth about 5/- per pound to fishermen.
    • The Fry of Salmon and Trout

      Anon. (Department of Agriculture, 1938)
      Every year large numbers of salmon fry (parr and smolts) are destroyed, sometimes quite unwittingly, by anglers who are unable to distinguish between salmon fry and young trout. Under Section 73 of the Fisheries (Ireland) Act, 1842, it is illegal to take the fry of either salmon or trout. The term “trout fry” has not yet received a legal interpretation but in some Fishery Districts the taking of immature trout below a certain size is prohibited by by-law. The fry of salmon are legally deemed to include also those fish locally called "jenkin" and "gravelling."
    • General Methods for Storage of Lobsters

      Gibson, F A (Department of Agriculture and Fisheries (Fisheries Division), 1972)
      This publication discusses the three types of storage unit used for holding lobsters in Ireland; (A) Tidal pounds (B) Recirculation or direct circulation pounds (C) High density units